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Min K.-E.,Advanced Welding and Joining Technology Center | Min K.-E.,Inha University | Lee J.-S.,Advanced Welding and Joining Technology Center | Yoo S.,Advanced Welding and Joining Technology Center | And 2 more authors.
Korean Journal of Materials Research | Year: 2010

The application of flip chip technology has been growing with the trend of miniaturization of electronic packages, especially in mobile electronics. Currently, several types of adhesive are used for flip chip bonding and these adhesives require some special properties; they must be solvent-free and fast curing and must ensure joint reliability against thermal fatigue and humidity. In this study, imidazole and its derivatives were added as curing catalysts to epoxy resin and their effects on the adhesive properties were investigated. Non-isothermal DSC analyses showed that the curing temperatures and the heat of reaction were dependent primarily on the type of catalyst. Isothermal dielectric analyses showed that the curing time was dependent on the amount of catalysts added as well as their type. The die shear strength increased with the increase of catalyst content while the Tg decreased. From this study, imidazole catalysts with low molecular weight are expected to be beneficial for snap curing and high adhesion strength for flip chip bonding applications.


Kwon S.-H.,Advanced Welding and Joining Technology Center | Kim K.-H.,Advanced Welding and Joining Technology Center | Seo W.-I.,Advanced Welding and Joining Technology Center | Park N.-S.,JESAGI HANKOOK Ltd. | And 3 more authors.
Proceedings - Electronic Components and Technology Conference | Year: 2013

Plasma coating for the surface finish of PCBs is a potential replacement of the conventional PCB finishes because of its environment-friendly process which does not produce any waster solution. In addition, the plasma surface finish enables to perform the multiple soldering over 5 times and shelf life is over 1 year. Corrosion properties of the plasma surface finish is higher than that of conventional surface finishes. In this study, solder joint properties were examined to understand the reliability of the plasma surface finish. Plasma surface finish was basically fluorine-based organic-inorganic composite thin films, which were deposited onto the Cu pads of a PCB. Sn-3.0Ag-0.5Cu (SAC305) solder was used as solder joint materials. Solder joint strength of the plasma finish sample was similar to that of the OSP finished sample. Plasma finishes had slightly higher brittle fracture rate after the multiple reflow test than OSP finish. In addition, plasma finish had higher corrosion resistance than OSP after a salt spray test. © 2013 IEEE.


Min K.-E.,Advanced Welding and Joining Technology Center | Kim H.-Y.,Advanced Welding and Joining Technology Center | Bang J.-H.,Advanced Welding and Joining Technology Center | Kim J.-H.,Advanced Welding and Joining Technology Center | Kim J.-K.,Advanced Welding and Joining Technology Center
Korean Journal of Materials Research | Year: 2011

As the performance of microelectronic devices is improved, the use of copper as a heat dissipation member is increasing due to its good thermal conductivity. The high thermal conductivity of copper, however, leads to difficulties in the joining process. Satisfactory bonding with copper is known to be difficult, especially if high shear and peel strengths are desired. The primary reason is that a copper oxide layer develops rapidly and is weakly attached to the base metal under typical conditions. Thus, when a clean copper substrate is bonded, the initial strength of the joint is high, but upon environmental exposure, an oxide layer may develop, which will reduce the durability of the joint. In this study, an epoxy adhesive formulation was investigated to improve the strength and reliability of a copper to copper joint. Epoxy hardeners such as anhydride, dihydrazide, and dicyandiamide and catalysts such as triphenylphosphine and imidazole were added to an epoxy resin mixture of DGEBA and DGEBF. Differential scanning calorimetry (DSC) analyses revealed that the curing temperatures were dependent on the type of hardener rather than on the catalyst,and higher heat of curing resulted in a higher Tg. The reliability of the copper joint against a high temperature and high humidity environment was found to be the lowest in the case of dihydrazide addition. This is attributed to its high water permeability, which led to the formation of a weak boundary layer of copper oxide. It was also found that dicyandiamide provided the highest initial joint strength and reliability while anhydride yielded intermediate performance between dicyandiamide and dihydrazide.

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